1. Field of the Invention
The present invention relates to a display device and more particularly relates to a display device for conducting a display operation in multiple primary colors.
2. Description of the Related Art
A color display device such as a color TV monitor or a color display monitor represents colors usually by adding together the three primary colors of red (R), green (G) and blue (b). Thus, each pixel in a color display device has red, green and blue subpixels for these three primary colors of RGB. YCrCb (YCC) signals, which can be converted into RGB signals, are input to such a display device and the red, green and blue subpixels change their luminances in response to the YCrCb signals, thereby representing various colors.
However, the color reproduction range of a normal display device is narrower than the range of the reproduced colors that can be perceived by human beings. That is why to expand the color reproduction range of a display device, various measures have been taken. For example, sometimes the color purity is increased by thickening color filters and sometimes LEDs with high color purity are used. According to these methods, however, either the brightness or the efficiency of the light source will decrease.
To overcome such problems, display devices that add together four or more primary colors, not just the three primary colors in display devices, have been proposed recently. Such a display device conducts a display operation using not just the three primary colors of RGB but also other additional primary colors, thereby expanding the color reproduction range. In such a display device, the luminances of respective subpixels are determined in response to video signals such as YCrCb signals and RGB signals. As a result, various colors can be represented (see PCT International Application Japanese National Phase Publication No. 2004-529396 and PCT International Application Japanese National Phase Publication No. 2005-523465, for example). In the six-primary-color display panel (which is an exemplary multi-primary-color display panel) disclosed in PCT International Application Japanese National Phase Publication No. 2004-529396 and PCT International Application Japanese National Phase Publication No. 2005-523465, a single pixel consists of six types of subpixels (namely, red, green, blue, yellow, cyan, and magenta subpixels), which are arranged either in line as shown in FIG. 32A or in two lines as shown in FIG. 32B.
Comparing the two arrangements of subpixels shown in FIGS. 32A and 32B, according to the arrangement of subpixels shown in FIG. 32A, subpixels of the same color are arranged far away from each other in the row direction as can be seen from FIG. 33A. That is why if the color red were displayed over the entire screen of such a display device, then red and black stripes would be quite visible in the column direction. On the other hand, according to the arrangement of subpixels shown in FIG. 32B, subpixels of the same color are arranged at short intervals in both the column and row directions as can be seen from FIG. 33B. Consequently, no stripes can be seen and the display quality does not deteriorate, either. For that reason, the subpixels are preferably arranged in multiple rows as shown in FIG. 32B.
However, if a multi-primary-color display panel with such an arrangement of pixels were fabricated at the same resolution as a three-primary-color display panel, then twice as many subpixels should be arranged vertically, thus increasing the cost and decreasing the aperture ratio. To overcome such problems, it has been proposed that a multi-primary-color display panel be fabricated as shown in FIG. 34B just by changing the color filters without changing the arrangement of current three-primary-color display panels as shown in FIG. 34A. Nevertheless, if such a multi-primary-color display panel is just used as it is, its vertical resolution will be only a half of that of a three-primary-color display panel and a high-definition display cannot be realized.